The invention is directed to a process and apparatus for automatically adjusting the testing position of an ultrasonic testing head in reference to the test piece in devices for testing work pieces without destruction, especially tubes, using a computer.
It is known that with a change in dimensions of test pieces, e.g. tubes, the ultrasonic head must be adjusted anew. In this connection important parameters of adjustment are, among others, the distance of the testing (examination) head to the object measured bearing in mind the testing head characteristics as well as the inclination of the testing head to the object being measured.
The adjustment of these parameters takes place manually, also partially by use of mechanical assisting devices. Thereby the operator is compelled to establish a most optimal possible test head piece substantially by tests. This is time consuming, requires experience and skill and above all in regard to reproducible adjustments with interim adjustment of the apparatus frequently proceeds very problematically. The manual adjustment takes place in such manner that, e.g. with tubes, inner and outer surface errors are evaluated with equal sensitivity in an echo evaluation unit. The evaluation of indications of error above all with the test head adjustment is undertaken based on an amplitude-transmission time-representation, normally on an oscillogram screen.
There have been attempts to reduce these expenses of change over and control times, to improve the reproductivity of the test results and to make the adjusting operation as independent as possible from service personnel. This is reported for example in the periodical "Material prufung", vol. 20 (1978), No. 4, pages 143-146, furthermore in the German Offenlegungsschrifts Nos. 2636401; 2632674 and 2632680. For this purpose the necessary electronic tests and evaluation programs are controlled by means of a computer. The decisive disadvantages described initially, the manual adjustments of the mechanics, however, remains.
Therefore it was the problem of the present invention to provide a process and apparatus for automatically adjusting the angle of inclination in the focus distance supersonic test heads in reference to the test piece in apparatus for testing work pieces, especially tubes, without destruction, using a computer, which avoids the above mentioned disadvantages and especially makes unnecessary a manual subsequent adjustment of the test head.